Can you even put more then 3 Phase conductors + ground or Neutral in a single conduit?? I've never seen it Done???HV ductbanks are derated by the number of conduits in the Ductbank not wires in the conduit.Figure 310.60 Page 342 NFPA Code handbook.70-159 NEC 2011

Tesla Sorry not Hypothetical. Read Field problem. Three 13.8 Switches single feed, Jumpers in between each (line side). Load off each switch proposed to run thur same nipple as feed to switch! I don't make this stuff up I run into it! Power calculations, Fill ect no problem. Yoopersup